Every once in a while, a car commercial captures the collective imagination -- all because of its soundtrack. This summer, it's Boston-based advertising agency Modernista!s sleek spot for Cadillac CTS, colloquially known as Metal and officially called "Accessories."

But what happens when the song in question is performed by a musical collective no one outside the ad industry has heard of? Pure chaos, apparently.



"Who else hasnt searched everywhere for this song now I know the name and artist, I just cant find it, even on their website!" bemoaned one YouTube.com commenter regarding the tune. "I want this song so bad, until I listen to it a few thousand times on my iPod I don't think I'll be able to get it out of my head," waxed another.



So, what is the song in question, and who is the artist performing the track? Black Iris, a seven-member-strong bicoastal collection of musicians (including session players who tour with acts such as the Walkmen and Foreign Born), is the band, and Firehydrant Floods is "that song." And as the MP3-savvy are discovering online, it is not yet available for download -- even on Black Iris own website -- despite ample proof of interest on message boards of several websites such as Yahoo! Answers and adtunes.com.



"I'm absolutely surprised at the response to this track," says Black Iris composer Justin Bailey, who may just be sitting on the next Days Go By," the tune tapped by Mitsubishi and its agency, Deutsch LA, in 2002 that launched the career of gold-selling trio Dirty Vegas.



"I'm glad to have written something that people are enjoying," the Virginia-based engineer wrote via e-mail from his studio earlier this week. "I had been listening to some of the dance music that's been coming out in the last few months, and it gave me the inspiration for an original idea with my own sonic footprint on it."



And while the full track is not yet available for download (the 30-second spot only uses "Firehydrant Floods' " siren-like main guitar riff; a catchy electro-rock pairing that sounds like a adrenalized, metal-tinged mix of Parisian duo Justice with Hum, whose 1995 hit "Stars" Moderintsa! has already resurrected in a separate commercial for Cadillac starring Kate Walsh), the riff alone has sent thousands scrambling to YouTube and the message boards of websites such as whatsthatcalled.com to find out where they can snag an MP3 of "Firehydrant Floods."



Of course, the full track, which Bailey wrote after he came up with the riff used in the commercial, exists -- it just hasn't been released yet, anywhere.



Black Iris Los Angeles-based co-founder, Daron Hollowell, has given Soundboard the full track this week exclusively. Next week, it will also be available on Black Iris' website.



Just dont blame us if the full song doesnt live up to your expectations.



"Being more of an 'indie rock' guy, I wanted to do some things with the drums that would feel more like what a real drummer would play as opposed to the more typical drum machine beats I heard on some of those tracks," Bailey said of "Firehydrant Floods," which was inspired by "feelings of summer, but a bit of a grittier feelings than the obvious sitting-by-the-beach image [of the season]."



Stream the full track here.



--Charlie Amter